Off-axis visualization systems

ABSTRACT

Off-axis visualization systems are described herein which facilitate the deployment, visualization, and retraction of an imaging element from a catheter. Such a system may include a deployment catheter and an attached imaging hood deployable into an expanded configuration as well as an imaging element, such as a CCD or CMOS imager, which may be deployed from a low profile configuration into a position which is off-axis relative to a longitudinal axis of the deployment catheter and/or imaging hood.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Prov. Pat. Apps.60/871,415 and 60/871,424 both filed Dec. 21, 2006, each of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to medical devices used forvisualizing and/or treating regions of tissue within a body. Moreparticularly, the present invention relates to methods and apparatus fordirectly visualizing tissue regions via imaging systems which areoff-axis relative to a longitudinal axis of a deployment catheter and/ortreating the issue regions under visualization.

BACKGROUND OF THE INVENTION

Conventional devices for accessing and visualizing interior regions of abody lumen are known. For example, ultrasound devices have been used toproduce images from within a body in vivo. Ultrasound has been used bothwith and without contrast agents, which typically enhanceultrasound-derived images.

Other conventional methods have utilized catheters or probes havingposition sensors deployed within the body lumen, such as the interior ofa cardiac chamber. These types of positional sensors are typically usedto determine the movement of a cardiac tissue surface or the electricalactivity within the cardiac tissue. When a sufficient number of pointshave been sampled by the sensors, a “map” of the cardiac tissue may begenerated.

Another conventional device utilizes an inflatable balloon which istypically introduced intravascularly in a deflated state and theninflated against the tissue region to be examined. Imaging is typicallyaccomplished by an optical fiber or other apparatus such as electronicchips for viewing the tissue through the membrane(s) of the inflatedballoon. Moreover, the balloon must generally be inflated for imaging.Other conventional balloons utilize a cavity or depression formed at adistal end of the inflated balloon. This cavity or depression is pressedagainst the tissue to be examined and is flushed with a clear fluid toprovide a clear pathway through the blood.

However, such imaging balloons have many inherent disadvantages. Forinstance, such balloons generally require that the balloon be inflatedto a relatively large size which may undesirably displace surroundingtissue and interfere with fine positioning of the imaging system againstthe tissue. Moreover, the working area created by such inflatableballoons are generally cramped and limited in size. Furthermore,inflated balloons may be susceptible to pressure changes in thesurrounding fluid. For example, if the environment surrounding theinflated balloon undergoes pressure changes, e.g., during systolic anddiastolic pressure cycles in a beating heart, the constant pressurechange may affect the inflated balloon volume and its positioning toproduce unsteady or undesirable conditions for optimal tissue imaging.

Accordingly, these types of imaging modalities are generally unable toprovide desirable images useful for sufficient diagnosis and therapy ofthe endoluminal structure, due in part to factors such as dynamic forcesgenerated by the natural movement of the heart. Moreover, anatomicstructures within the body can occlude or obstruct the image acquisitionprocess. Also, the presence and movement of opaque bodily fluids such asblood generally make in vivo imaging of tissue regions within the heartdifficult.

Other external imaging modalities are also conventionally utilized. Forexample, computed tomography (CT) and magnetic resonance imaging (MRI)are typical modalities which are widely used to obtain images of bodylumens such as the interior chambers of the heart. However, such imagingmodalities fail to provide real-time imaging for intra-operativetherapeutic procedures. Fluoroscopic imaging, for instance, is widelyused to identify anatomic landmarks within the heart and other regionsof the body. However, fluoroscopy fails to provide an accurate image ofthe tissue quality or surface and also fails to provide forinstrumentation for performing tissue manipulation or other therapeuticprocedures upon the visualized tissue regions. In addition, fluoroscopyprovides a shadow of the intervening tissue onto a plate or sensor whenit may be desirable to view the intraluminal surface of the tissue todiagnose pathologies or to perform some form of therapy on it.

Moreover, many of the conventional imaging systems lack the capabilityto provide therapeutic treatments or are difficult to manipulate inproviding effective therapies. For instance, the treatment in apatient's heart for atrial fibrillation is generally made difficult by anumber of factors, such as visualization of the target tissue, access tothe target tissue, and instrument articulation and management, amongstothers.

Conventional catheter techniques and devices, for example such as thosedescribed in U.S. Pat. Nos. 5,895,417; 5,941,845; and 6,129,724, used onthe epicardial surface of the heart may be difficult in assuring atransmural lesion or complete blockage of electrical signals. Inaddition, current devices may have difficulty dealing with varyingthickness of tissue through which a transmural lesion desired.

Conventional accompanying imaging devices, such as fluoroscopy, areunable to detect perpendicular electrode orientation, catheter movementduring the cardiac cycle, and image catheter position throughout lesionformation. Without real-time visualization, it is difficult toreposition devices to another area that requires transmural lesionablation. The absence of real-time visualization also poses the risk ofincorrect placement and ablation of critical structures such as sinusnode tissue which can lead to fatal consequences.

Thus, a tissue imaging system which is able to provide real-time in vivoaccess to and images of tissue regions within body lumens such as theheart through opaque media such as blood and which also providesinstruments for therapeutic procedures are desirable.

SUMMARY OF THE INVENTION

The tissue-imaging apparatus described relates to variations of a deviceand/or method to provide real-time images in vivo of tissue regionswithin a body lumen such as a heart, which is filled with blood flowingdynamically therethrough. Such an apparatus may be utilized for manyprocedures, e.g., mitral valvuloplasty, left atrial appendage closure,arrhythmia ablation, transseptal access and patent foramen ovale closureamong other procedures. Further details of such a visualization catheterand methods of use are shown and described in U.S. Pat. Pub.2006/0184048 A1, which is incorporated herein by reference in itsentirety.

A tissue imaging and manipulation apparatus that may be utilized forprocedures within a body lumen, such as the heart, in whichvisualization of the surrounding tissue is made difficult, if notimpossible, by medium contained within the lumen such as blood, isdescribed below. Generally, such a tissue imaging and manipulationapparatus comprises an optional delivery catheter or sheath throughwhich a deployment catheter and imaging hood may be advanced forplacement against or adjacent to the tissue to be imaged.

The deployment catheter may define a fluid delivery lumen therethroughas well as an imaging lumen within which an optical imaging fiber orelectronic imaging assembly may be disposed for imaging tissue. Whendeployed, the imaging hood may be expanded into any number of shapes,e.g., cylindrical, conical as shown, semi-spherical, etc., provided thatan open area or field is defined by the imaging hood. The open area isthe area within which the tissue region of interest may be imaged. Theimaging hood may also define an atraumatic contact lip or edge forplacement or abutment against the tissue region of interest. Moreover,the distal end of the deployment catheter or separate manipulatablecatheters may be articulated through various controlling mechanisms suchas push-pull wires manually or via computer control

In operation, after the imaging hood has been deployed, fluid may bepumped at a positive pressure through the fluid delivery lumen until thefluid fills the open area completely and displaces any blood from withinthe open area. The fluid may comprise any biocompatible fluid, e.g.,saline, water, plasma, Fluorinert™, etc., which is sufficientlytransparent to allow for relatively undistorted visualization throughthe fluid. The fluid may be pumped continuously or intermittently toallow for image capture by an optional processor which may be incommunication with the assembly.

The imaging hood may be deployed into an expanded shape and retractedwithin a catheter utilizing various mechanisms. Moreover, the imagingelement, such as a CCD or CMOS imaging camera, may be positioneddistally or proximally of the imaging hood when collapsed into itslow-profile configuration. Such a configuration may reduce or eliminatefriction during deployment and retraction as well as increase theavailable space within the catheter not only for the imaging unit butalso for the hood.

Moreover, the imaging element may be introduced along or within the hoodinto an off-axis position relative to a longitudinal axis of thecatheter and/or hood for providing direct visualization of theunderlying tissue to be visually examined and/or treated. For example,one variation may utilize a flexible section located at a distal end ofthe catheter which may be configured from various flexible materialscoupled or integrated with a relatively rigid section located proximallyof flexible section. The imaging element may be positioned and/orattached to a lateral inner wall of the flexible section such that whenthe section is collapsed within the sheath, the imaging element may beplaced in an in-line or axially positioned relative to the catheter andhood to provide for a low-profile delivery configuration.

Upon deployment of the hood from the constraints of the sheath, the hoodand flexible section may be advanced distal to the sheath such that thehood is free to expand or to be expanded and the flexible section isalso unconstrained to expand or to be expanded as well such that aportion of the flexible section extends laterally relative to the hoodand the catheter to form an imager retaining channel or pocket. Theretaining channel or pocket may extend laterally a sufficient distance,either self-expanding or pushed open via the imager being urgedlaterally into the space, such that the space distal to the catheter isunobstructed by the imager or retaining channel. Alternatively, if theflexible section is self-expanding when pushed out of the sheath suchthat it expands to its original lateral configuration when notconstrained by the sheath, the section may urge imager into its off-axisposition if attached to one another.

Because the imager is positioned laterally, the catheter and hood mayaccommodate a variety of sizes for different types of imagers. Forinstance, relatively larger, more economical, and/or relatively morepowerful CCD or CMOS imagers may be utilized with the system as the hoodmay accommodate a range of sizes and configurations for the imagingsystem. With the imager positioned in its off-axis location relative tothe hood and/or catheter, the user may obtain a better angle ofvisualization of the entire operating landscape, including both themovements of the tools and the target tissue surface during any numberof therapeutic and/or diagnostic procedures. Moreover, the unobstructedopening of the catheter may allow for various instruments, such as RFablation probes, graspers, needles, etc., to be deployed through thecatheter and past the imager into the open area defined by the hood fortreatment upon the underlying imaged tissue.

Various other configurations for positioning the imaging elementoff-axis may include us of instruments such as a dilator positionedproximal to the flexible segment. The dilator may be translatablethrough the deployment catheter and may also define one or more workinglumens therethrough for the introduction of one or more instruments.With the imaging element attached laterally within the channel orpocket, the hood and flexible section may be advanced out of the sheathwith the imaging element still in its low-profile axial position. Thedilator may be pushed distally to expand the collapsed section to itsexpanded volume to form the channel or pocket, consequently pushing theimaging element laterally to the side where the imaging element maybulge out and stretch the channel or pocket.

Yet other variations may utilize an imager support member which isextendable through the deployment catheter and the collapsed imaginghood to position the imaging element distally of the hood. When the hoodis deployed and expanded, the imaging element may be pulled proximallyinto the hood and into its off-axis position via the support member,which may include one or more curved or linked sections or which may bemade from a shape memory alloy which reconfigures itself. In yet anothervariation, the imaging element may include a tapered or angled proximalsurface which is forced to slide against an angled surface which iscomplementary to the imaging element surface. Proximal actuation of theimager may force the imaging element to slide into an off-axis position.In yet other variations, the imaging element may be urged into itsoff-axis position via an inflatable elongate balloon which pushes theimager along or within the hood.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a side view of one variation of a tissue imaging apparatusduring deployment from a sheath or delivery catheter.

FIG. 1B shows the deployed tissue imaging apparatus of FIG. 1A having anoptionally expandable hood or sheath attached to an imaging and/ordiagnostic catheter.

FIG. 1C shows an end view of a deployed imaging apparatus.

FIGS. 1D to 1F show the apparatus of FIGS. 1A to 1C with an additionallumen, e.g., for passage of a guidewire therethrough.

FIGS. 2A and 2B show one example of a deployed tissue imager positionedagainst or adjacent to the tissue to be imaged and a flow of fluid, suchas saline, displacing blood from within the expandable hood.

FIG. 3A shows an articulatable imaging assembly which may be manipulatedvia push-pull wires or by computer control.

FIGS. 3B and 3C show steerable instruments, respectively, where anarticulatable delivery catheter may be steered within the imaging hoodor a distal portion of the deployment catheter itself may be steered.

FIGS. 4A to 4C show side and cross-sectional end views, respectively, ofanother variation having an off-axis imaging capability.

FIGS. 4D and 4E show examples of various visualization imagers which maybe utilized within or along the imaging hood.

FIG. 5 shows an illustrative view of an example of a tissue imageradvanced intravascularly within a heart for imaging tissue regionswithin an atrial chamber.

FIGS. 6A to 6C illustrate deployment catheters having one or moreoptional inflatable balloons or anchors for stabilizing the deviceduring a procedure.

FIGS. 7A and 7B illustrate a variation of an anchoring mechanism such asa helical tissue piercing device for temporarily stabilizing the imaginghood relative to a tissue surface.

FIG. 7C shows another variation for anchoring the imaging hood havingone or more tubular support members integrated with the imaging hood;each support members may define a lumen therethrough for advancing ahelical tissue anchor within.

FIG. 8A shows an illustrative example of one variation of how a tissueimager may be utilized with an imaging device.

FIG. 8B shows a further illustration of a hand-held variation of thefluid delivery and tissue manipulation system.

FIGS. 9A to 9C illustrate an example of capturing several images of thetissue at multiple regions.

FIGS. 10A and 10B show charts illustrating how fluid pressure within theimaging hood may be coordinated with the surrounding blood pressure; thefluid pressure in the imaging hood may be coordinated with the bloodpressure or it may be regulated based upon pressure feedback from theblood.

FIGS. 11A to 11C show side, perspective, and end views, respectively, ofone variation of the tissue visualization catheter having a collapsedflexible section proximal to or along the hood or barrier or membrane.

FIGS. 12A to 12C show side, perspective, and end views, respectively, ofthe catheter having the hood expanded and an imaging element positionedoff-axis relative to a longitudinal axis of the catheter into theexpanded flexible section which forms a retaining channel or pocket.

FIG. 13 illustrates a perspective view of the hood placed against atissue region of interest with the imager providing direct visualizationof the underlying tissue while positioned in its off-axis configuration.

FIGS. 14A and 14B show another variation where the imaging element ispositionable in its off-axis configuration via an instrument such as adilator positioned proximal to the flexible segment.

FIGS. 14C and 14D show partial cross-sectional side views of the dilatorpositioned proximally of the imaging element.

FIGS. 14E to 14G show side, perspective, and detail perspective views,respectively, of the dilator pushed distally through the flexiblesegment to expand the work channel allowing tools to pass through andalso pushing the imaging element off-axis relative to the catheterlongitudinal axis.

FIG. 15 shows a side view of a visualization catheter where the dilatorinstrument may be preformed into a curved or arcuate shape such that thesheath and/or deployment catheter conforms into the curved or arcuateshape.

FIGS. 16A and 16B show side views of another variation having theflexible section proximal to the hood and defining a slit near or alonga distal end of the work channel for expandably receiving the imagingelement which protrudes distally from the sheath when in its low-profileconfiguration.

FIGS. 16C and 16D show perspective and detailed perspective views,respectively, of the visualization catheter where the slit and flexibleportion may protrude distally of the sheath for deployment.

FIGS. 17A to 17C show side, perspective, and detailed perspective views,respectively, of the deployed hood and the imaging element pushed pastthe slit and positioned off-axis relative to the hood and catheterlongitudinal axis.

FIGS. 18A and 18B show side views of another variation of the tissuevisualization catheter with an imaging element positioned distal to thecollapsed hood in the retracted configuration within the sheath and alsoupon hood deployment.

FIGS. 18C and 18D show side and perspective views of the imaging elementurged into its off-axis configuration when pulled proximally through thehood and into the receiving channel or pocket.

FIGS. 19A and 19B show side views of another variation of the tissuevisualization catheter with an imaging element positioned distal to thecollapsed hood within a sheath via an imager support member comprised ofa shape memory alloy and in a deployed configuration where the supportmember articulates into an off-axis configuration.

FIGS. 19C and 19D show partial cross-sectional side and perspectiveviews, respectively, of the imaging element pulled proximally into thehood in its off-axis configuration.

FIG. 20 shows a perspective view of the visualization catheter placedagainst a tissue surface for affecting a therapeutic procedure underoff-axis visualization.

FIGS. 21A and 21B show partial cross-sectional side views of thevisualization catheter with the imaging element disposed distally of thecollapsed hood and pulled proximally against a tapered interface withinthe deployed hood.

FIGS. 21C and 21D show side and perspective views, respectively, of thedeployed hood and imaging element actuated into its off-axisconfiguration by the angled interface between the imaging elementhousing and distal end of the internal deployment catheter.

FIG. 22 shows a perspective view of the visualization catheter placedagainst a tissue surface with the off-axis camera providing an elevatedoff-axis image to better estimate tool movements during therapeuticprocedures.

FIGS. 23A and 23B show partial cross-sectional side views of an imagingelement attached to a hinged cantilever member and disposed distally ofa collapsed hood and the deployed hood.

FIGS. 24A to 24C show side, detailed side, and perspective views,respectively, where the imaging element is positioned in an off-axisconfiguration by the hinged cantilever member actuated via a pullwire.

FIG. 25 shows a perspective view of the visualization catheter placedagainst a tissue surface with the off-axis imaging element providing anelevated off-axis image to better estimate tool movements duringtherapeutic procedures.

FIGS. 26A and 26B show partial cross-sectional side views of thevisualization catheter with the imaging element disposed distally of thecollapsed hood and being rotated into its off-axis configuration via itsrotatable imager support member.

FIGS. 27A and 27B show side and perspective views, respectively, wherethe imaging element is positioned in an off-axis configuration by therotated support member.

FIG. 28 shows a perspective view of the visualization catheter placedagainst a tissue surface with the imaging element providing an elevatedoff-axis image to better estimate tool movement during therapeuticprocedures.

FIGS. 29A and 29B show partial cross-sectional side views of anothervariation of the visualization catheter where the imaging element may beattached to the hood via an elastic member such that retraction of theimaging element facilitates collapse of the hood and withdrawal of theimaging element facilitates deployment of the hood.

FIGS. 30A and 30B show partial cross-sectional side views of anothervariation of the tissue visualization catheter where the imaging elementis translatably coupled or attached along a strut of the hood.

FIGS. 31A and 31B show a partial cross-sectional side view of anothervariation of the tissue visualization catheter where the imaging elementmay be attached upon a distal end of one or more inflatable balloonswhich may be inflated to position the imaging element along the hood.

FIGS. 32A and 32B show side views of another variation of an imaginghood having an expandable channel or pocket positioned along the hoodfor accommodating the imaging element.

DETAILED DESCRIPTION OF THE INVENTION

A tissue-imaging and manipulation apparatus described below is able toprovide real-time images in vivo of tissue regions within a body lumensuch as a heart, which is filled with blood flowing dynamicallytherethrough and is also able to provide intravascular tools andinstruments for performing various procedures upon the imaged tissueregions. Such an apparatus may be utilized for many procedures, e.g.,facilitating transseptal access to the left atrium, cannulating thecoronary sinus, diagnosis of valve regurgitation/stenosis,valvuloplasty, atrial appendage closure, arrhythmogenic focus ablation,among other procedures. Further examples of tissue visualizationcatheters which may be utilized are shown and described in furtherdetail in U.S. patent application Ser. No. 11/259,498 filed Oct. 25,2005, which has been incorporated hereinabove by reference in itsentirety.

One variation of a tissue access and imaging apparatus is shown in thedetail perspective views of FIGS. 1A to 1C. As shown in FIG. 1A, tissueimaging and manipulation assembly 10 may be delivered intravascularlythrough the patient's body in a low-profile configuration via a deliverycatheter or sheath 14. In the case of treating tissue, such as themitral valve located at the outflow tract of the left atrium of theheart, it is generally desirable to enter or access the left atriumwhile minimizing trauma to the patient. To non-operatively effect suchaccess, one conventional approach involves puncturing the intra-atrialseptum from the right atrial chamber to the left atrial chamber in aprocedure commonly called a transseptal procedure or septostomy. Forprocedures such as percutaneous valve repair and replacement,transseptal access to the left atrial chamber of the heart may allow forlarger devices to be introduced into the venous system than cangenerally be introduced percutaneously into the arterial system.

When the imaging and manipulation assembly 10 is ready to be utilizedfor imaging tissue, imaging hood 12 may be advanced relative to catheter14 and deployed from a distal opening of catheter 14, as shown by thearrow. Upon deployment, imaging hood 12 may be unconstrained to expandor open into a deployed imaging configuration, as shown in FIG. 1B.Imaging hood 12 may be fabricated from a variety of pliable orconformable biocompatible material including but not limited to, e.g.,polymeric, plastic, or woven materials. One example of a woven materialis Kevlar® (E. I. du Pont de Nemours, Wilmington, Del.), which is anaramid and which can be made into thin, e.g., less than 0.001 in.,materials which maintain enough integrity for such applicationsdescribed herein. Moreover, the imaging hood 12 may be fabricated from atranslucent or opaque material and in a variety of different colors tooptimize or attenuate any reflected lighting from surrounding fluids orstructures, i.e., anatomical or mechanical structures or instruments. Ineither case, imaging hood 12 may be fabricated into a uniform structureor a scaffold-supported structure, in which case a scaffold made of ashape memory alloy, such as Nitinol, or a spring steel, or plastic,etc., may be fabricated and covered with the polymeric, plastic, orwoven material. Hence, imaging hood 12 may comprise any of a widevariety of barriers or membrane structures, as may generally be used tolocalize displacement of blood or the like from a selected volume of abody lumen or heart chamber. In exemplary embodiments, a volume withinan inner surface 13 of imaging hood 12 will be significantly less than avolume of the hood 12 between inner surface 13 and outer surface 11.

Imaging hood 12 may be attached at interface 24 to a deployment catheter16 which may be translated independently of deployment catheter orsheath 14. Attachment of interface 24 may be accomplished through anynumber of conventional methods. Deployment catheter 16 may define afluid delivery lumen 18 as well as an imaging lumen 20 within which anoptical imaging fiber or assembly may be disposed for imaging tissue.When deployed, imaging hood 12 may expand into any number of shapes,e.g., cylindrical, conical as shown, semi-spherical, etc., provided thatan open area or field 26 is defined by imaging hood 12. The open area 26is the area within which the tissue region of interest may be imaged.Imaging hood 12 may also define an atraumatic contact lip or edge 22 forplacement or abutment against the tissue region of interest. Moreover,the diameter of imaging hood 12 at its maximum fully deployed diameter,e.g., at contact lip or edge 22, is typically greater relative to adiameter of the deployment catheter 16 (although a diameter of contactlip or edge 22 may be made to have a smaller or equal diameter ofdeployment catheter 16). For instance, the contact edge diameter mayrange anywhere from 1 to 5 times (or even greater, as practicable) adiameter of deployment catheter 16. FIG. 1C shows an end view of theimaging hood 12 in its deployed configuration. Also shown are thecontact lip or edge 22 and fluid delivery lumen 18 and imaging lumen 20.

The imaging and manipulation assembly 10 may additionally define aguidewire lumen therethrough, e.g., a concentric or eccentric lumen, asshown in the side and end views, respectively, of FIGS. 1D to 1F. Thedeployment catheter 16 may define guidewire lumen 19 for facilitatingthe passage of the system over or along a guidewire 17, which may beadvanced intravascularly within a body lumen. The deployment catheter 16may then be advanced over the guidewire 17, as generally known in theart.

In operation, after imaging hood 12 has been deployed, as in FIG. 1B,and desirably positioned against the tissue region to be imaged alongcontact edge 22, the displacing fluid may be pumped at positive pressurethrough fluid delivery lumen 18 until the fluid fills open area 26completely and displaces any fluid 28 from within open area 26. Thedisplacing fluid flow may be laminarized to improve its clearing effectand to help prevent blood from re-entering the imaging hood 12.Alternatively, fluid flow may be started before the deployment takesplace. The displacing fluid, also described herein as imaging fluid, maycomprise any biocompatible fluid, e.g., saline, water, plasma, etc.,which is sufficiently transparent to allow for relatively undistortedvisualization through the fluid. Alternatively or additionally, anynumber of therapeutic drugs may be suspended within the fluid or maycomprise the fluid itself which is pumped into open area 26 and which issubsequently passed into and through the heart and the patient body.

As seen in the example of FIGS. 2A and 2B, deployment catheter 16 may bemanipulated to position deployed imaging hood 12 against or near theunderlying tissue region of interest to be imaged, in this example aportion of annulus A of mitral valve MV within the left atrial chamber.As the surrounding blood 30 flows around imaging hood 12 and within openarea 26 defined within imaging hood 12, as seen in FIG. 2A, theunderlying annulus A is obstructed by the opaque blood 30 and isdifficult to view through the imaging lumen 20. The translucent fluid28, such as saline, may then be pumped through fluid delivery lumen 18,intermittently or continuously, until the blood 30 is at leastpartially, and preferably completely, displaced from within open area 26by fluid 28, as shown in FIG. 2B.

Although contact edge 22 need not directly contact the underlyingtissue, it is at least preferably brought into close proximity to thetissue such that the flow of clear fluid 28 from open area 26 may bemaintained to inhibit significant backflow of blood 30 back into openarea 26. Contact edge 22 may also be made of a soft elastomeric materialsuch as certain soft grades of silicone or polyurethane, as typicallyknown, to help contact edge 22 conform to an uneven or rough underlyinganatomical tissue surface. Once the blood 30 has been displaced fromimaging hood 12, an image may then be viewed of the underlying tissuethrough the clear fluid 30. This image may then be recorded or availablefor real-time viewing for performing a therapeutic procedure. Thepositive flow of fluid 28 may be maintained continuously to provide forclear viewing of the underlying tissue. Alternatively, the fluid 28 maybe pumped temporarily or sporadically only until a clear view of thetissue is available to be imaged and recorded, at which point the fluidflow 28 may cease and blood 30 may be allowed to seep or flow back intoimaging hood 12. This process may be repeated a number of times at thesame tissue region or at multiple tissue regions.

In desirably positioning the assembly at various regions within thepatient body, a number of articulation and manipulation controls may beutilized. For example, as shown in the articulatable imaging assembly 40in FIG. 3A, one or more push-pull wires 42 may be routed throughdeployment catheter 16 for steering the distal end portion of the devicein various directions 46 to desirably position the imaging hood 12adjacent to a region of tissue to be visualized. Depending upon thepositioning and the number of push-pull wires 42 utilized, deploymentcatheter 16 and imaging hood 12 may be articulated into any number ofconfigurations 44. The push-pull wire or wires 42 may be articulated viatheir proximal ends from outside the patient body manually utilizing oneor more controls. Alternatively, deployment catheter 16 may bearticulated by computer control, as further described below.

Additionally or alternatively, an articulatable delivery catheter 48,which may be articulated via one or more push-pull wires and having animaging lumen and one or more working lumens, may be delivered throughthe deployment catheter 16 and into imaging hood 12. With a distalportion of articulatable delivery catheter 48 within imaging hood 12,the clear displacing fluid may be pumped through delivery catheter 48 ordeployment catheter 16 to clear the field within imaging hood 12. Asshown in FIG. 3B, the articulatable delivery catheter 48 may bearticulated within the imaging hood to obtain a better image of tissueadjacent to the imaging hood 12. Moreover, articulatable deliverycatheter 48 may be articulated to direct an instrument or tool passedthrough the catheter 48, as described in detail below, to specific areasof tissue imaged through imaging hood 12 without having to repositiondeployment catheter 16 and re-clear the imaging field within hood 12.

Alternatively, rather than passing an articulatable delivery catheter 48through the deployment catheter 16, a distal portion of the deploymentcatheter 16 itself may comprise a distal end 49 which is articulatablewithin imaging hood 12, as shown in FIG. 3C. Directed imaging,instrument delivery, etc., may be accomplished directly through one ormore lumens within deployment catheter 16 to specific regions of theunderlying tissue imaged within imaging hood 12.

Visualization within the imaging hood 12 may be accomplished through animaging lumen 20 defined through deployment catheter 16, as describedabove. In such a configuration, visualization is available in astraight-line manner, i.e., images are generated from the field distallyalong a longitudinal axis defined by the deployment catheter 16.Alternatively or additionally, an articulatable imaging assembly havinga pivotable support member 50 may be connected to, mounted to, orotherwise passed through deployment catheter 16 to provide forvisualization off-axis relative to the longitudinal axis defined bydeployment catheter 16, as shown in FIG. 4A. Support member 50 may havean imaging element 52, e.g., a CCD or CMOS imager or optical fiber,attached at its distal end with its proximal end connected to deploymentcatheter 16 via a pivoting connection 54.

If one or more optical fibers are utilized for imaging, the opticalfibers 58 may be passed through deployment catheter 16, as shown in thecross-section of FIG. 4B, and routed through the support member 50. Theuse of optical fibers 58 may provide for increased diameter sizes of theone or several lumens 56 through deployment catheter 16 for the passageof diagnostic and/or therapeutic tools therethrough. Alternatively,electronic chips, such as a charge coupled device (CCD) or a CMOSimager, which are typically known, may be utilized in place of theoptical fibers 58, in which case the electronic imager may be positionedin the distal portion of the deployment catheter 16 with electric wiresbeing routed proximally through the deployment catheter 16.Alternatively, the electronic imagers may be wirelessly coupled to areceiver for the wireless transmission of images. Additional opticalfibers or light emitting diodes (LEDs) can be used to provide lightingfor the image or operative theater, as described below in furtherdetail. Support member 50 may be pivoted via connection 54 such that themember 50 can be positioned in a low-profile configuration withinchannel or groove 60 defined in a distal portion of catheter 16, asshown in the cross-section of FIG. 4C. During intravascular delivery ofdeployment catheter 16 through the patient body, support member 50 canbe positioned within channel or groove 60 with imaging hood 12 also inits low-profile configuration. During visualization, imaging hood 12 maybe expanded into its deployed configuration and support member 50 may bedeployed into its off-axis configuration for imaging the tissue adjacentto hood 12, as in FIG. 4A. Other configurations for support member 50for off-axis visualization may be utilized, as desired.

FIG. 4D shows a partial cross-sectional view of an example where one ormore optical fiber bundles 62 may be positioned within the catheter andwithin imaging hood 12 to provide direct in-line imaging of the openarea within hood 12. FIG. 4E shows another example where an imagingelement 64 (e.g., CCD or CMOS electronic imager) may be placed along aninterior surface of imaging hood 12 to provide imaging of the open areasuch that the imaging element 64 is off-axis relative to a longitudinalaxis of the hood 12. The off-axis position of element 64 may provide fordirect visualization and uninhibited access by instruments from thecatheter to the underlying tissue during treatment.

FIG. 5 shows an illustrative cross-sectional view of a heart H havingtissue regions of interest being viewed via an imaging assembly 10. Inthis example, delivery catheter assembly 70 may be introducedpercutaneously into the patient's vasculature and advanced through thesuperior vena cava SVC and into the right atrium RA. The deliverycatheter or sheath 72 may be articulated through the atrial septum ASand into the left atrium LA for viewing or treating the tissue, e.g.,the annulus A, surrounding the mitral valve MV. As shown, deploymentcatheter 16 and imaging hood 12 may be advanced out of delivery catheter72 and brought into contact or in proximity to the tissue region ofinterest. In other examples, delivery catheter assembly 70 may beadvanced through the inferior vena cava IVC, if so desired. Moreover,other regions of the heart H, e.g., the right ventricle RV or leftventricle LV, may also be accessed and imaged or treated by imagingassembly 10.

In accessing regions of the heart H or other parts of the body, thedelivery catheter or sheath 14 may comprise a conventionalintra-vascular catheter or an endoluminal delivery device.Alternatively, robotically-controlled delivery catheters may also beoptionally utilized with the imaging assembly described herein, in whichcase a computer-controller 74 may be used to control the articulationand positioning of the delivery catheter 14. An example of arobotically-controlled delivery catheter which may be utilized isdescribed in further detail in US Pat. Pub. 2002/0087169 A1 to Brock etal. entitled “Flexible Instrument”, which is incorporated herein byreference in its entirety. Other robotically-controlled deliverycatheters manufactured by Hansen Medical, Inc. (Mountain View, Calif.)may also be utilized with the delivery catheter 14.

To facilitate stabilization of the deployment catheter 16 during aprocedure, one or more inflatable balloons or anchors 76 may bepositioned along the length of catheter 16, as shown in FIG. 6A. Forexample, when utilizing a transseptal approach across the atrial septumAS into the left atrium LA, the inflatable balloons 76 may be inflatedfrom a low-profile into their expanded configuration to temporarilyanchor or stabilize the catheter 16 position relative to the heart H.FIG. 6B shows a first balloon 78 inflated while FIG. 6C also shows asecond balloon 80 inflated proximal to the first balloon 78. In such aconfiguration, the septal wall AS may be wedged or sandwiched betweenthe balloons 78, 80 to temporarily stabilize the catheter 16 and imaginghood 12. A single balloon 78 or both balloons 78, 80 may be used. Otheralternatives may utilize expandable mesh members, malecots, or any othertemporary expandable structure. After a procedure has been accomplished,the balloon assembly 76 may be deflated or re-configured into alow-profile for removal of the deployment catheter 16.

To further stabilize a position of the imaging hood 12 relative to atissue surface to be imaged, various anchoring mechanisms may beoptionally employed for temporarily holding the imaging hood 12 againstthe tissue. Such anchoring mechanisms may be particularly useful forimaging tissue which is subject to movement, e.g., when imaging tissuewithin the chambers of a beating heart. A tool delivery catheter 82having at least one instrument lumen and an optional visualization lumenmay be delivered through deployment catheter 16 and into an expandedimaging hood 12. As the imaging hood 12 is brought into contact againsta tissue surface T to be examined, anchoring mechanisms such as ahelical tissue piercing device 84 may be passed through the tooldelivery catheter 82, as shown in FIG. 7A, and into imaging hood 12.

The helical tissue engaging device 84 may be torqued from its proximalend outside the patient body to temporarily anchor itself into theunderlying tissue surface T. Once embedded within the tissue T, thehelical tissue engaging device 84 may be pulled proximally relative todeployment catheter 16 while the deployment catheter 16 and imaging hood12 are pushed distally, as indicated by the arrows in FIG. 7B, to gentlyforce the contact edge or lip 22 of imaging hood against the tissue T.The positioning of the tissue engaging device 84 may be lockedtemporarily relative to the deployment catheter 16 to ensure securepositioning of the imaging hood 12 during a diagnostic or therapeuticprocedure within the imaging hood 12. After a procedure, tissue engagingdevice 84 may be disengaged from the tissue by torquing its proximal endin the opposite direction to remove the anchor form the tissue T and thedeployment catheter 16 may be repositioned to another region of tissuewhere the anchoring process may be repeated or removed from the patientbody. The tissue engaging device 84 may also be constructed from otherknown tissue engaging devices such as vacuum-assisted engagement orgrasper-assisted engagement tools, among others.

Although a helical anchor 84 is shown, this is intended to beillustrative and other types of temporary anchors may be utilized, e.g.,hooked or barbed anchors, graspers, etc. Moreover, the tool deliverycatheter 82 may be omitted entirely and the anchoring device may bedelivered directly through a lumen defined through the deploymentcatheter 16.

In another variation where the tool delivery catheter 82 may be omittedentirely to temporarily anchor imaging hood 12, FIG. 7C shows an imaginghood 12 having one or more tubular support members 86, e.g., foursupport members 86 as shown, integrated with the imaging hood 12. Thetubular support members 86 may define lumens therethrough each havinghelical tissue engaging devices 88 positioned within. When an expandedimaging hood 12 is to be temporarily anchored to the tissue, the helicaltissue engaging devices 88 may be urged distally to extend from imaginghood 12 and each may be torqued from its proximal end to engage theunderlying tissue T. Each of the helical tissue engaging devices 88 maybe advanced through the length of deployment catheter 16 or they may bepositioned within tubular support members 86 during the delivery anddeployment of imaging hood 12. Once the procedure within imaging hood 12is finished, each of the tissue engaging devices 88 may be disengagedfrom the tissue and the imaging hood 12 may be repositioned to anotherregion of tissue or removed from the patient body.

An illustrative example is shown in FIG. 8A of a tissue imaging assemblyconnected to a fluid delivery system 90 and to an optional processor 98and image recorder and/or viewer 100. The fluid delivery system 90 maygenerally comprise a pump 92 and an optional valve 94 for controllingthe flow rate of the fluid into the system. A fluid reservoir 96,fluidly connected to pump 92, may hold the fluid to be pumped throughimaging hood 12. An optional central processing unit or processor 98 maybe in electrical communication with fluid delivery system 90 forcontrolling flow parameters such as the flow rate and/or velocity of thepumped fluid. The processor 98 may also be in electrical communicationwith an image recorder and/or viewer 100 for directly viewing the imagesof tissue received from within imaging hood 12. Imager recorder and/orviewer 100 may also be used not only to record the image but also thelocation of the viewed tissue region, if so desired.

Optionally, processor 98 may also be utilized to coordinate the fluidflow and the image capture. For instance, processor 98 may be programmedto provide for fluid flow from reservoir 96 until the tissue area hasbeen displaced of blood to obtain a clear image. Once the image has beendetermined to be sufficiently clear, either visually by a practitioneror by computer, an image of the tissue may be captured automatically byrecorder 100 and pump 92 may be automatically stopped or slowed byprocessor 98 to cease the fluid flow into the patient. Other variationsfor fluid delivery and image capture are, of course, possible and theaforementioned configuration is intended only to be illustrative and notlimiting.

FIG. 8B shows a further illustration of a hand-held variation of thefluid delivery and tissue manipulation system 110. In this variation,system 110 may have a housing or handle assembly 112 which can be heldor manipulated by the physician from outside the patient body. The fluidreservoir 114, shown in this variation as a syringe, can be fluidlycoupled to the handle assembly 112 and actuated via a pumping mechanism116, e.g., lead screw. Fluid reservoir 114 may be a simple reservoirseparated from the handle assembly 112 and fluidly coupled to handleassembly 112 via one or more tubes. The fluid flow rate and othermechanisms may be metered by the electronic controller 118.

Deployment of imaging hood 12 may be actuated by a hood deploymentswitch 120 located on the handle assembly 112 while dispensation of thefluid from reservoir 114 may be actuated by a fluid deployment switch122, which can be electrically coupled to the controller 118. Controller118 may also be electrically coupled to a wired or wireless antenna 124optionally integrated with the handle assembly 112, as shown in thefigure. The wireless antenna 124 can be used to wirelessly transmitimages captured from the imaging hood 12 to a receiver, e.g., viaBluetooth® wireless technology (Bluetooth SIG, Inc., Bellevue, Wash.),RF, etc., for viewing on a monitor 128 or for recording for laterviewing.

Articulation control of the deployment catheter 16, or a deliverycatheter or sheath 14 through which the deployment catheter 16 may bedelivered, may be accomplished by computer control, as described above,in which case an additional controller may be utilized with handleassembly 112. In the case of manual articulation, handle assembly 112may incorporate one or more articulation controls 126 for manualmanipulation of the position of deployment catheter 16. Handle assembly112 may also define one or more instrument ports 130 through which anumber of intravascular tools may be passed for tissue manipulation andtreatment within imaging hood 12, as described further below.Furthermore, in certain procedures, fluid or debris may be sucked intoimaging hood 12 for evacuation from the patient body by optionallyfluidly coupling a suction pump 132 to handle assembly 112 or directlyto deployment catheter 16.

As described above, fluid may be pumped continuously into imaging hood12 to provide for clear viewing of the underlying tissue. Alternatively,fluid may be pumped temporarily or sporadically only until a clear viewof the tissue is available to be imaged and recorded, at which point thefluid flow may cease and the blood may be allowed to seep or flow backinto imaging hood 12. FIGS. 9A to 9C illustrate an example of capturingseveral images of the tissue at multiple regions. Deployment catheter 16may be desirably positioned and imaging hood 12 deployed and broughtinto position against a region of tissue to be imaged, in this examplethe tissue surrounding a mitral valve MV within the left atrium of apatient's heart. The imaging hood 12 may be optionally anchored to thetissue, as described above, and then cleared by pumping the imagingfluid into the hood 12. Once sufficiently clear, the tissue may bevisualized and the image captured by control electronics 118. The firstcaptured image 140 may be stored and/or transmitted wirelessly 124 to amonitor 128 for viewing by the physician, as shown in FIG. 9A.

The deployment catheter 16 may be then repositioned to an adjacentportion of mitral valve MV, as shown in FIG. 9B, where the process maybe repeated to capture a second image 142 for viewing and/or recording.The deployment catheter 16 may again be repositioned to another regionof tissue, as shown in FIG. 9C, where a third image 144 may be capturedfor viewing and/or recording. This procedure may be repeated as manytimes as necessary for capturing a comprehensive image of the tissuesurrounding mitral valve MV, or any other tissue region. When thedeployment catheter 16 and imaging hood 12 is repositioned from tissueregion to tissue region, the pump may be stopped during positioning andblood or surrounding fluid may be allowed to enter within imaging hood12 until the tissue is to be imaged, where the imaging hood 12 may becleared, as above.

As mentioned above, when the imaging hood 12 is cleared by pumping theimaging fluid within for clearing the blood or other bodily fluid, thefluid may be pumped continuously to maintain the imaging fluid withinthe hood 12 at a positive pressure or it may be pumped under computercontrol for slowing or stopping the fluid flow into the hood 12 upondetection of various parameters or until a clear image of the underlyingtissue is obtained. The control electronics 118 may also be programmedto coordinate the fluid flow into the imaging hood 12 with variousphysical parameters to maintain a clear image within imaging hood 12.

One example is shown in FIG. 10A which shows a chart 150 illustratinghow fluid pressure within the imaging hood 12 may be coordinated withthe surrounding blood pressure. Chart 150 shows the cyclical bloodpressure 156 alternating between diastolic pressure 152 and systolicpressure 154 over time T due to the beating motion of the patient heart.The fluid pressure of the imaging fluid, indicated by plot 160, withinimaging hood 12 may be automatically timed to correspond to the bloodpressure changes 160 such that an increased pressure is maintainedwithin imaging hood 12 which is consistently above the blood pressure156 by a slight increase ΔP, as illustrated by the pressure differenceat the peak systolic pressure 158. This pressure difference, ΔP, may bemaintained within imaging hood 12 over the pressure variance of thesurrounding blood pressure to maintain a positive imaging fluid pressurewithin imaging hood 12 to maintain a clear view of the underlyingtissue. One benefit of maintaining a constant ΔP is a constant flow andmaintenance of a clear field.

FIG. 10B shows a chart 162 illustrating another variation formaintaining a clear view of the underlying tissue where one or moresensors within the imaging hood 12, as described in further detailbelow, may be configured to sense pressure changes within the imaginghood 12 and to correspondingly increase the imaging fluid pressurewithin imaging hood 12. This may result in a time delay, ΔT, asillustrated by the shifted fluid pressure 160 relative to the cyclingblood pressure 156, although the time delays ΔT may be negligible inmaintaining the clear image of the underlying tissue. Predictivesoftware algorithms can also be used to substantially eliminate thistime delay by predicting when the next pressure wave peak will arriveand by increasing the pressure ahead of the pressure wave's arrival byan amount of time equal to the aforementioned time delay to essentiallycancel the time delay out.

The variations in fluid pressure within imaging hood 12 may beaccomplished in part due to the nature of imaging hood 12. An inflatableballoon, which is conventionally utilized for imaging tissue, may beaffected by the surrounding blood pressure changes. On the other hand,an imaging hood 12 retains a constant volume therewithin and isstructurally unaffected by the surrounding blood pressure changes, thusallowing for pressure increases therewithin. The material that hood 12is made from may also contribute to the manner in which the pressure ismodulated within this hood 12. A stiffer hood material, such as highdurometer polyurethane or Nylon, may facilitate the maintaining of anopen hood when deployed. On the other hand, a relatively lower durometeror softer material, such as a low durometer PVC or polyurethane, maycollapse from the surrounding fluid pressure and may not adequatelymaintain a deployed or expanded hood.

As mentioned above, an imaging element, e.g., a CCD or CMOS imager oroptical fiber, may be connected to, mounted to, or otherwise passedthrough deployment catheter 16 to provide for visualization off-axisrelative to the longitudinal axis 186 defined by deployment catheter 16.In yet other variations for providing off-axis visualization, an imagingelement may be advanced through or along deployment catheter 16 suchthat the imaging element and hood 12 are arranged to be delivered in alow-profile configuration within sheath 14. Upon deployment of hood 12,the imaging element may be introduced along or within hood 12 into anoff-axis position relative to the longitudinal axis of catheter 16 forproviding direct visualization of the underlying tissue to be visuallyexamined and/or treated.

FIGS. 11A and 11B illustrate partial cross-sectional side andperspective views, respectively, of one variation of an imaging systemwhich may be positioned off-axis relative to the longitudinal axis 186of deployment catheter 16. As shown in its low-profile configuration,hood 12 may be collapsed within lumen 176 of sheath 14 and attached tocatheter 16, which in this variation may include a flexible section 170located at a distal end of catheter 16 and which may be configured fromvarious flexible materials coupled or integrated with a relatively rigidsection 172 located proximally of flexible section 170. Alternatively,the flexible section 170 may be coupled or integrated to a proximalportion of hood 12. The flexible section 170 may be made from variouselastomers or conformable polymers such as silicone, polyvinyl chloride(PVC), polyurethane (PU), polyethylene terephthalate (PET), flexiblepolymeric tubes reinforced with Nitinol, etc.

In either case, imaging element 174 (e.g., CCD, CMOS, optical fiber,etc.) may be positioned and/or attached to a lateral inner wall offlexible section 170 such that when section 170 is collapsed withinsheath 14, as shown, imaging element 174 may be placed in an in-line oraxial positioned relative to the catheter 16 and hood 12 to provide fora low-profile delivery configuration, as also shown in the end view ofFIG. 11C.

Upon deployment of hood 12 from the constraints of sheath 14, hood 12and flexible section 170 may be advanced distal to sheath 14 such thathood 12 is free to expand or to be expanded and flexible section 170 isalso unconstrained to expand or to be expanded as well such that aportion of flexible section 170 extends laterally relative to hood 12and catheter 16 to form an imager retaining channel or pocket 178, asshown in the side and perspective views of FIGS. 12A and 12B. Retainingchannel or pocket 178 may extend laterally a sufficient distance, eitherself-expanding or pushed open via imager 174 being urged laterally intothe space, such that the space distal to catheter 16 is unobstructed byimager 174 or retaining channel 178, as shown in the end view of FIG.12C. Alternatively, if flexible section 170 is self-expanding whenpushed out of the sheath 14 such that it expands to its original lateralconfiguration when not constrained by sheath 14, section 170 may urgeimager 174 into its off-axis position if attached to one another.

Because imager 174 is positioned laterally, catheter 16 and hood 12 mayaccommodate a variety of sizes for different types of imagers 174. Forinstance, relatively larger, more economical, and/or relatively morepowerful CCD or CMOS imagers may be utilized with the system as hood 12may accommodate a range of sizes and configurations for the imagingsystem. With the imager 174 positioned in its off-axis location relativeto the hood 12 and/or catheter 16, the user may obtain a better angle ofvisualization of the entire operating landscape, including both themovements of the tools and the target tissue surface during any numberof therapeutic and/or diagnostic procedures. Moreover, the unobstructedopening of catheter 16 may allow for various instruments, such as RFablation probes 182, graspers, needles, etc., to be deployed throughcatheter 16 and past imager 174 into the open area defined by hood 12for treatment upon the underlying imaged tissue.

FIG. 13 illustrates a perspective view of hood 12 placed against atissue region of interest T with the imager 174 providing directvisualization of the underlying tissue T while positioned in itsoff-axis configuration. As described above, the clearing fluid 28 may bepumped into the open area defined by hood 12 to purge the surroundingblood from hood 12 and to provide a clear transparent imaging field (asindicated by the field of view 184) within hood 12, as provided byimager 174. Ablation probe 182 is illustrated as having been advancedthrough a working lumen of catheter 16, past the off-axis imager 174,and into the interior of hood 12 to treat the underlying tissue T whileunder direct visualization.

Another variation for an off-axis visualization system is shown in thepartial cross-sectional side views of FIGS. 14A and 14B, whichillustrate an imaging element 174 which is positionable in its off-axisconfiguration via an instrument such as a dilator 190 positionedproximal to the flexible segment 170, as shown in the perspective viewsof FIGS. 14C and 14D. Dilator may be translatable through deploymentcatheter 16 and may also define one or more working lumens 192, 194, 196therethrough for the introduction of one or more instruments. Withimaging element 174 attached laterally within channel or pocket 178,hood 12 and flexible section 170 may be advanced out of sheath 14 withimaging element 174 still in its low-profile axial position.

As shown in FIGS. 14E to 14G, which show side, perspective, and detailperspective views, respectively, dilator 190 may be pushed distally toexpand the collapsed section 170 to its expanded volume to form channelor pocket 178, consequently pushing imaging element 174 laterally to theside where imaging element 174 may bulge out and stretch channel orpocket 178. With the distal end of the work channel unobstructed,various instruments such as RF ablation probe 182, graspers, needles,etc. can be deployed forward into the open area enclosed by the expandedhood 12.

A variety of dilators may also be used with deployment catheter 16and/or sheath 14. Dilators may define single or multiple lumensaccording to the needs of the user and the size of the instruments to beused with the tissue visualization catheter. Accordingly, differentdilators can be conveniently and quickly swapped while hood 12 is stillin the patient's body. In addition, dilators which are preformed to havea curved or arcuate shape may also be used such that catheter 16 and/orsheath 14 may conform into the curved or arcuate shape imparted by thedilator, as shown in FIG. 15. This can be especially useful forprocedures such as transseptal puncture of the septal wall.

In yet another variation, FIGS. 16A and 16B show partial cross-sectionalside views of hood 12 in its retracted configuration within sheath 14and in its expanded configuration. In this variation, imaging element174 may be positioned upon an imager support member 200 which maycomprise a wire frame or support fabricated from any number ofmaterials, e.g., Nitinol, stainless steel, titanium, etc. which extendsthrough catheter 16. In its low-profile configuration, imaging element174 may be positioned distally of the collapsed hood 12 by extendingsupport member 200. Having imaging element 174 positioned distal to hood12 when retracted in sheath 14 may allow for hood 12 and sheath 14 toaccommodate various configurations and sizes of imaging element 174.

Once hood 12 has been expanded, support member 200 may be pulledproximally to bring imaging element 174 into hood 12 and into itsoff-axis position. To receive imaging element 174 within hood 12, theflexible section proximal to hood 12 may define a longitudinal slit 202at least partially along the section, as shown in the perspective anddetailed perspective views of FIGS. 16C and 16D. When imaging element174 is pulled proximally into hood 12, imaging element 174 may slidein-between slit 202 consequently expanding the slit 202 to allow forimaging element 174 to bulge laterally into its off-axis position andform receiving channel or pocket 178, as shown in the side andperspective views of FIGS. 17A to 17C. Any number of instruments maythen be advanced into and/or through hood 12 past the off-axis imagingelement 174.

Another variation is illustrated in the side views of FIGS. 18A and 18Bwhich show imaging element 174 attached to imager support member 210. Inits low-profile configuration and its initial deployed configuration,imaging element 174 may be positioned distal to hood 12 while connectedvia support member 210 to allow for sheath 14 to accommodate relativelylarger sized imaging elements. Support member 210 may pass proximallythrough side opening 212 defined along a side surface of catheter 16adjacent to where receiving channel or pocket 178 is located. Thus, oncehood 12 has been expanded, support member 210 may be pulled proximallythrough opening 212 to draw imaging element 174 proximally directly intoreceiving channel or pocket 178 such that imaging element 174 ispositioned into its off-axis location, as shown in the side andperspective views of FIGS. 18C and 18D. With imaging element 174 andsupport member 210 withdrawn, any number of instruments such as ablationprobe 182 may be advanced into hood 12 to treat the underlying tissue inan unobstructed field.

FIGS. 19A and 19B illustrate yet another variation where imaging element174 may be positioned upon an imager support member 220 fabricated froma shape memory alloy, e.g., Nitinol, which is pre-shaped with an angledor off-axis segment 222 to position imaging element 174 into an off-axisposition when freed from the constraints of sheath 14. FIG. 19Aillustrates imaging element 174 positioned distally of the collapsedhood 12 with the support member 220 extended forward. Alignment ofimaging element 174 in this manner allows for hood 12 to be collapsedcompletely and thus frees up additional space within the lumen of sheath14. As hood 12 is expanded, angled or off-axis segment 222 mayreconfigure into its relaxed shape where imaging element 174 is movedinto its off-axis configuration, as indicated by the direction ofmovement 224 in FIG. 19B. Support member 220 may then be pulledproximally into hood 12 such that imaging element 174 is positionedalong an inner surface of hood 12 in an off-axis configuration, asillustrated in the partial cross-sectional side and perspective views ofFIGS. 19C and 19D. To withdraw imaging element 174, support member 220may be advanced distally of hood 12, which may be collapsed proximallyof imaging element 174 and both hood 12 and imaging element 174 may bepulled proximally into sheath 14, which may constrain angled or off-axissegment 222 back into its low-profile configuration.

FIG. 20 illustrates a perspective view of deployed hood 12 positionedupon a tissue region of interest T with imaging element 174 positionedinto its off-axis configuration via support member 220.

Yet another variation is illustrated in the partial cross-sectional sideviews of FIGS. 21A and 21B which illustrate imaging element 174 which isattached to imager support member 234 and positioned distal to collapsedhood 12. The proximal surface of imaging element 174 may have an angledor tapered surface 230 which extends at a first angle relative todeployment catheter 16. The distal end of catheter 16 may also define areceiving surface 232 which is angled or tapered at an anglecomplementary to surface 230. With hood 12 in its expandedconfiguration, support member 234 may be pulled proximally such thattapered surface 230 of imaging element 174 is drawn into contact againstreceiving surface 232, as illustrated in FIG. 21B.

Upon further tensioning of support member 234, imaging element 174 maybe forced to slide proximally along the tapered interface and into itsoff-axis location, as indicated by the angled direction of travel 236 inthe cross-sectional side view of FIG. 21C. By moving the imaging element174 off-axis, the area in front of the working lumen 238 of deploymentcatheter 16 is cleared for any number of instruments, such as ablationprobe 182, to be deployed through as illustrated in the perspective viewof FIG. 21D. FIG. 22 illustrates the imaging element 174 angled into itsoff-axis position via the tapered or angled interface between taperedsurface 230 of imaging element 174 and receiving surface 232 whilevisualizing the underlying tissue to be treated via ablation probe 182.

FIGS. 23A and 23B show yet another variation where imaging element 174may be positioned distal to collapsed hood 12 while attached to acantilevered support member 240. FIG. 23B shows how imaging element 174may be withdrawn proximally into hood 12 from its distal position oncehood 12 has been expanded. Once imaging element 174 has beensufficiently withdrawn, a pullwire 242 made from a material such asNitinol, stainless steel, titanium, etc. and attached to imaging element174 and passing through an opening or slot 248 defined through supportmember 240 may be tensioned through deployment catheter 16, as shown inthe detailed perspective view of FIG. 24B. Cantilevered support member240 may define a first notch or hinge 244, e.g., a living hinge, along afirst side of member 240 and a second notch or hinge 246, e.g., also aliving hinge, along a second side of member 240 along an opposite sideto where first notch or groove 244 is defined and proximal to firstnotch or groove 244, as shown in FIG. 24A. Thus, when pullwire 242 istensioned to pull imaging element 174 proximally, cantilevered supportmember 240 may be forced to reconfigure from its straightenedconfiguration such that member 240 bends at notches 244, 246 into anangled configuration to reposition imaging element 174 into its off-axisposition, as shown in the side and perspective views of FIGS. 24A and24C. Upon relaxing pullwire 242, support member 240 may reconfigure backinto its straightened low-profile shape.

FIG. 25 illustrates a perspective view of deployed hood 12 positionedupon a tissue region of interest T with imaging element 174 positionedinto its off-axis configuration via cantilevered support member 240 withpullwire 242 under tension.

In yet another variation, FIGS. 26A and 26B illustrate partialcross-sectional side views of an imaging element 174 positioned distalto the collapsed hood 12 in a low-profile configuration shown in FIG.26A where imaging element 174 is attached to imager support member 250which is rotatable about its longitudinal axis. A distal portion ofsupport member 250 may define a curved off-axis section 252 which alignsimaging element 174 eccentrically relative to catheter 16 such that whensupport member 250 is rotated, e.g., 180 degrees, imaging element 174 isrotated into an off-axis position, as indicated by the direction ofrotation 254 illustrated in FIG. 26B. Off-axis section 252 of supportmember 250 may be angled along its length at two or more locations andit may be fabricated from any number of materials, such as Nitinol,stainless steel, titanium, etc.

FIGS. 27A and 27B show side and perspective views of imaging element 174having been rotated into its off-axis position with support member 250withdrawn proximally into hood 12 such that imaging element 174 ispositioned along an inner surface of hood 12. With the space distal todeployment catheter 16 unobstructed by imaging element 174, any numberof instruments may be advanced into hood 12, such as ablation probe 182,to be utilized upon the underlying tissue while visualized via imagingelement 174.

FIG. 28 illustrates a perspective view of deployed hood 12 positionedupon a tissue region of interest T with imaging element 174 positionedinto its off-axis configuration via angled support member 250 imagingthe underlying tissue within the open area of hood 12 through atransparent fluid while also treating the tissue with ablation probe182.

Another variation is illustrated in the partial cross-sectional sideviews of FIGS. 29A and 29B which show imaging element 174 coupled to thedistal end of shaft 266, which may optionally also include an instrument270 positioned upon its distal end, such as a helical tissue grasper,ablation probe, needle, or other instrument. Imaging element 174 may becoupled to the distal end of shaft 266 via linkage member 268 which isfree to pivot relative to both imaging element 174 and shaft 266, e.g.,via living hinges, pivots, etc. An elastic member 260 (e.g., siliconerubber, latex, polyurethane, or other common elastomers) may also coupleimaging element 174 at attachment point 262 to the inner surface of hood12 at attachment point 264. By pulling proximally on shaft 266 throughcatheter 16, as indicated by the direction of imager retraction 272,linkage member 268 may pull imaging element 174 proximally into a workchannel of catheter 16. This may subsequently stretch elastic member 260connecting imaging element 174 and hood 12 resulting in elastic member260 pulling hood 12 into its low-profile collapsed configuration beforeor while hood 12 is retracted into sheath 14, as indicated by thedirection of hood collapse 274. Hence imaging element 174 may bepositioned proximal to and in line with hood 12, by positioning itwithin a working lumen rather than wrapped within the collapsed hood 12when retracted into sheath 14.

To deploy hood 12, the process may be reversed where shaft 266 may beurged distally to push linkage member 268, which in turn may pushimaging element 174 distally. As hood 12 is deployed, elastic member 260may pull imaging element into its off-axis position along the innersurface of hood 12.

FIGS. 30A and 30B illustrate yet another variation in the partialcross-sectional side views where imaging element 174 is attached tolinkage member 280, which is also slidingly connected to strut 282,which in turn is positioned along an inner surface of hood 12. When hood12 is in its collapsed configuration, imaging element 174 may bepositioned distal to hood 12 via linkage member 280, as shown in FIG.30A. A magnet 284 (e.g., ferrous magnet or electromagnet) may bepositioned along or at the distal end of sheath 14 such that magnet 284is integrated with sheath 14 or placed along an outer or inner surfaceof sheath 14. The housing of imaging element 174 may be fabricated froma magnetically attractive and/or ferromagnetic material such that whenhood 12 is deployed distally from sheath 14, the magnetic attractionbetween the housing of imaging element 174 and magnet 284 maymagnetically pull imaging element 174. As hood 12 is deployed fromsheath 14, imaging element 174 may slide or roll proximally along strut282, which may be connected to one another via a translatable coupling286, until imaging element 174 is slid to a proximal position alongstrut 282, as shown in FIG. 30B. In this proximal position, imagingelement 174 may be positioned in its off-axis configuration relative tocatheter 16 and hood 12.

When hood 12 is retracted into sheath 14, magnet 284 may magneticallyattract imaging element 174 such that hood 12 is collapsed proximally ofimaging element 174 and is positioned distally of the collapsed hood 12when retained within sheath 14, thus freeing up additional space withinsheath 14.

FIGS. 31A and 31B illustrate partial cross-sectional side views ofanother variation where hood 12 may define an elongate channel 292within or along the length of hood 12. Once hood 12 has been deployedfrom sheath 14 into its expanded configuration, an elongate balloon 290having imaging element 174 attached to its distal end may be inflatedwithin channel 292 such that balloon 290 propagates distally andadvances imaging element 174 into the hood 12, as shown in FIG. 31B.Balloon 290 may be fabricated from various elastomeric materials such asC-flex, ChronoPrene, silicone or polyurethene, etc. Moreover, channel292 may be constructed by enclosing the balloon 290 between two layersof heat welded material, e.g., Mylar or PET sheets, such that the weldedsheets form a cylindrical lumen through which balloon 290 may expandalong the axis of channel 292 when inflated. The assembly of balloon290, imaging element 174, and channel 292 may then be mounted on theinner wall of hood 12, e.g., by an adhesive.

FIGS. 32A and 32B show side views, respectively, of another variation ofimaging hood 12 modified to have an expandable channel or pocket 300positioned along hood 12. In this configuration, one or more hoodsupport struts or members 304 may be positioned along hood 12 to providestructural support. When imaging element 174 and hood 12 are collapsedin their low-profile configuration, imaging element 174 may bepositioned distal to hood 12 with control member 302, e.g., cables,wires, etc., connected to imaging element 174 and passing throughchannel or pocket 300. With imaging element 174 positioned distal toexpanded hood 12, as shown in FIG. 32A, imaging element 174 may bepulled proximally via member 302 into channel or pocket 300 such thatthe imager 174 slides and squeezes itself into pocket 300, which itselfmay bulge out laterally to the side of hood 12, as shown in FIG. 32B.With the camera positioned laterally of hood 12 when deployed, a clearfield of visualization is provided.

The applications of the disclosed invention discussed above are notlimited to certain treatments or regions of the body, but may includeany number of other treatments and areas of the body. Modification ofthe above-described methods and devices for carrying out the invention,and variations of aspects of the invention that are obvious to those ofskill in the arts are intended to be within the scope of thisdisclosure. Moreover, various combinations of aspects between examplesare also contemplated and are considered to be within the scope of thisdisclosure as well.

1. A system for visualizing a tissue region of interest, comprising: adeployment catheter defining at least one lumen therethrough; a barrieror membrane projecting distally from the deployment catheter anddefining an open area therein, wherein the open area is in fluidcommunication with the at least one lumen; an imaging element forvisualizing tissue adjacent to the open area; and a flexible sectionpositioned proximally or adjacent to the barrier or membrane and whichforms a channel for receiving the imaging element upon deployment of thebarrier or membrane such that the imaging element is positioned off-axisrelative to a longitudinal axis of the catheter.
 2. The system of claim1 further comprising a sheath slidably disposed over the deploymentcatheter.
 3. The system of claim 1 further comprising an ablation probepassing through the deployment catheter.
 4. The system of claim 1wherein the imaging element is attached to an inner surface of thechannel such that the imaging element is pulled into its off-axisposition via the channel.
 5. The system of claim 1 wherein the flexiblesection defines an expandable slit through which the imaging element ispositionable upon deployment of the barrier or membrane.
 6. The systemof claim 1 further comprising a dilator positioned proximally of theimaging element such that advancement of the dilator through thecatheter forces the imaging element into the channel in its off-axisposition.
 7. The system of claim 1 further comprising a support memberattached to the imaging element and slidably extendable through thebarrier or membrane, wherein proximal withdrawal of the support memberpositions the imaging element in its off-axis position.
 8. The system ofclaim 7 wherein the support member is comprised of a shape memory alloyhaving a curved configuration along its distal end such thatreconfiguring the support member from a straightened low-profileconfiguration positions the imaging element in its off-axis position. 9.The system of claim 7 wherein the support member is comprised of ahinged linkage member which is configured to pivot or bend therealongsuch that tensioning of a pullwire positions the imaging element intoits off-axis position.
 10. The system of claim 7 wherein the supportmember defines a curved or bent portion such that rotation of thesupport member about its longitudinal axis positions the imaging elementinto its off-axis position.
 11. The system of claim 1 wherein a proximalsurface of the imaging element is tapered or angled and wherein a distalsurface of the deployment catheter is tapered or angled in acomplementary interface such that proximal withdrawal of the imagingelement relative to the deployment catheter slides the imaging elementalong the interface into its off-axis position.
 12. The system of claim1 wherein the channel extends proximally from an outer surface of thebarrier or membrane.
 13. A method of visualizing a tissue region ofinterest, comprising: placing an open area of a barrier or membraneextending from a deployment catheter against or adjacent to a tissueregion; positioning an imaging element from a low-profile configurationwherein the imaging element is positioned axially with respect to acollapsed barrier or membrane and into an off-axis position within oralong a deployed barrier or membrane relative to a longitudinal axis ofthe catheter; displacing an opaque fluid with a transparent fluid fromthe open area defined by the barrier or membrane and the tissue region;and visualizing the tissue region through the transparent fluid via theoff-axis imaging element.
 14. The method of claim 13 further comprisingintravascularly advancing the barrier or membrane in its low-profileconfiguration prior to placing an open area.
 15. The method of claim 13wherein positioning an imaging element comprises receiving the imagingelement within a channel defined by an expanded flexible sectionpositioned proximally or adjacent to the barrier or membrane.
 16. Themethod of claim 15 wherein receiving the imaging element comprisesforcing the imaging element into the channel via an instrument.
 17. Themethod of claim 15 wherein receiving the imaging element comprisesproximally withdrawing the imaging element via a support member into thechannel.
 18. The method of claim 13 wherein positioning an imagingelement comprises proximally withdrawing the imaging element via asupport member into the channel, wherein the support member defines acurved or bent distal end.
 19. The method of claim 13 whereinpositioning an imaging element comprises actuating a linkage memberattached to the imaging element via a pullwire into the off-axisposition.
 20. The method of claim 13 further comprising treating thetissue region via an ablation probe while visualizing.